Fan blades

ABSTRACT

A blade for an axial fan, including at least a front edge portion, a back edge portion, and multiple pressure balance holes. The front edge portion operates to blow air from the outside of the blade, the back edge portion operates to blow air to the outside of the blade, and the pressure balance hole is disposed on the back edge portion. The pressure balance holes are adapted to balance pressure and reduce pressure difference between the front side and the back side of the blade, eliminating backflow phenomenon caused by separation of boundary layer airflow at the back edge portion on a windward side of the blade and thus reducing power consumption and noise, and preventing dust from settling on the back edge portion on the windward side of the blade.

CROSS-REFERENCE TO RELATED APPLICATIONS

Pursuant to 35 U.S.C. §119 and the Paris Convention Treaty, thisapplication claims the benefit of Chinese Patent Application No.200810187034.0 filed on Dec. 11, 2008, the contents of which areincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a blade for an axial fan and a blade for acentrifugal fan.

2. Description of the Related Art

As shown in FIG. 1, a conventional blade for an axial fan comprises afront edge portion and a back edge portion. The front edge portionoperates to blow air from the outside of the blade, and the back edgeportion operates to blow air to the outside of the blade. However, thereare several problems with the blade: as the blade rotates, the airflowat the back edge portion is affected with increase of rotary kineticenergy, as a result, separation of boundary layer airflow causes abackflow phenomena when the airflow is discharged from the back edgeportion, which increases power consumption and noise, and a great dealof dust is settled on the back edge portion on a windward side of theblade.

As for a conventional blade for a centrifugal fan, the same problems asabove exist.

SUMMARY OF THE INVENTION

In view of the above-described problem, it is one objective of theinvention to provide a conventional blade for an axial fan that iscapable of eliminating a backflow phenomena caused by separation ofboundary layer airflow, reducing power consumption and noise, andpreventing dust from being settled on a back edge portion on a windwardside of the blade.

It is another objective of the invention to provide a conventional bladefor a centrifugal fan that is capable of eliminating a backflowphenomena caused by separation of boundary layer airflow, reducing powerconsumption and noise, and preventing dust from being settled on a backedge portion on a windward side of the blade.

To achieve the above objectives, in accordance with one embodiment ofthe invention, provided is a blade for an axial fan, comprising a frontedge portion, a back edge portion, and multiple pressure balance holes.The front edge portion operates to blow air from the outside of theblade, the back edge portion operates to blow air to the outside of theblade, and the pressure balance hole is disposed on the back edgeportion.

In a class of this embodiment, the pressure balance holes aredistributed in an array, uniformly or randomly.

In a class of this embodiment, the pressure balance holes are straightthrough holes or inclined through holes.

In a class of this embodiment, the pressure balance holes form a holenet whereby adjusting pressure on both side of the blade.

In a class of this embodiment, a diameter of the pressure balance holeranges from 0.1 mm to 100 mm.

In a class of this embodiment, the pressure balance hole is a circularhole or a non-circular hole.

In accordance with another embodiment of the invention, provided is ablade for a centrifugal fan, comprising a front edge portion, a backedge portion, and multiple pressure balance holes. The front edgeportion operates to blow air from the outside of the blade, the backedge portion operates to blow air to the outside of the blade, and thepressure balance hole is disposed on the back edge portion.

In a class of this embodiment, the pressure balance holes aredistributed in an array, uniformly or randomly.

In a class of this embodiment, the pressure balance holes are straightthrough holes or inclined through holes.

In a class of this embodiment, the pressure balance holes form a holenet whereby adjusting pressure on both side of the blade.

In a class of this embodiment, a diameter of the pressure balance holeranges from 0.1 mm to 100 mm.

In a class of this embodiment, the pressure balance hole is a circularhole or a non-circular hole.

Advantages of the blade for an axial fan of the invention comprise: 1)the pressure balance holes disposed on the back edge portion are capableof balancing pressure and reducing pressure difference between a frontside and a back side of the blade; 2) the pressure balance holes arecapable of eliminating a backflow phenomena caused by separation ofboundary layer airflow at the back edge portion on a windward side ofthe blade and thus reducing power consumption and noise; 3) the pressurebalance holes are capable of preventing dust from being settled on aback edge portion on a windward side of the blade.

Advantages of the blade for a centrifugal fan of the inventioncomprise: 1) the pressure balance holes disposed on the back edgeportion are capable of balancing pressure and reducing pressuredifference between a front side and a back side of the blade; 2) thepressure balance holes are capable of eliminating a backflow phenomenacaused by separation of boundary layer airflow at the back edge portionon a windward side of the blade and thus reducing power consumption andnoise; 3) the pressure balance holes are capable of preventing dust frombeing settled on a back edge portion on a windward side of the blade.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described hereinafter with reference to accompanyingdrawings, in which:

FIG. 1 is a schematic view of an axial fan in the prior art;

FIG. 2 is a schematic view of a blade for an axial fan of an exemplaryembodiment of the invention;

FIG. 3 illustrates an application of an axial fan of an exemplaryembodiment of the invention;

FIG. 4 is a schematic view of a centrifugal fan of another exemplaryembodiment of the invention; and

FIG. 5 is a schematic view of a blade for a centrifugal fan of anotherexemplary embodiment of the invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

As shown in FIGS. 2 and 3, a blade for an axial fan of the inventioncomprises a front edge portion 1, a back edge portion 2, and multiplepressure balance holes 3. The front edge portion 1 operates to blow airfrom the outside of the blade, the back edge portion 2 operates to blowair to the outside of the blade, and the pressure balance hole 3 isdisposed on the back edge portion 2.

The pressure balance holes 3 are distributed in an array, uniformly orrandomly.

In this embodiment, the pressure balance holes 3 are circular holes,non-circular holes, straight through holes or inclined through holes,and a diameter of each of the pressure balance holes 3 ranges from 0.1mm to 100 mm.

The pressure balance holes 3 form a hole net whereby adjusting pressureon both side of the blade.

The pressure balance holes 3 are capable of balancing pressure andreducing pressure difference between a front side and a back side of theblade, eliminating a backflow phenomena caused by separation of boundarylayer airflow at the back edge portion 2 on a windward side 4 of theblade and thus reducing power consumption and noise, and preventing dustfrom being settled on the back edge portion 2 on the windward side 4 ofthe blade.

As shown in FIGS. 4 and 5, a blade for a centrifugal fan of theinvention comprises a front edge portion 1, a back edge portion 2, andmultiple pressure balance holes 3. The front edge portion 1 operates toblow air from the outside of the blade, the back edge portion 2 operatesto blow air to the outside of the blade, and the pressure balance hole 3is disposed on the back edge portion 2.

The pressure balance holes 3 are distributed in an array, uniformly orrandomly.

In this embodiment, the pressure balance holes 3 are circular holes,non-circular holes, straight through holes or inclined through holes,and a diameter of each of the pressure balance holes 3 ranges from 0.1mm to 100 mm.

The pressure balance holes 3 form a hole net whereby adjusting pressureon both side of the blade.

The pressure balance holes 3 are capable of balancing pressure andreducing pressure difference between a front side and a back side of theblade, eliminating a backflow phenomena caused by separation of boundarylayer airflow at the back edge portion 2 on a windward side 4 of theblade and thus reducing power consumption and noise, and preventing dustfrom being settled on the back edge portion 2 on the windward side 4 ofthe blade.

While particular embodiments of the invention have been shown anddescribed, it will be obvious to those skilled in the art that changesand modifications may be made without departing from the invention inits broader aspects, and therefore, the aim in the appended claims is tocover all such changes and modifications as fall within the true spiritand scope of the invention.

1. A blade for an axial fan, comprising a front edge portion; a backedge portion; and multiple pressure balance holes; wherein said frontedge portion operates to blow air from the outside of the blade; saidback edge portion operates to blow air to the outside of the blade; andsaid pressure balance hole is disposed on said back edge portion.
 2. Theblade of claim 1, wherein said pressure balance holes are distributed inan array, uniformly or randomly.
 3. The blade of claim 1, wherein saidpressure balance holes are circular holes, non-circular holes, straightthrough holes or inclined through holes.
 4. The blade of claim 1,wherein said pressure balance holes form a hole net whereby adjustingpressure on both side of the blade.
 5. The blade of claim 1, wherein adiameter of said pressure balance hole ranges from 0.1 mm to 100 mm. 6.The blade of claim 1, wherein said pressure balance hole is a circularhole or a non-circular hole.
 7. A blade for a centrifugal fan,comprising a front edge portion; a back edge portion; and multiplepressure balance holes; wherein said front edge portion operates to blowair from the outside of the blade; said back edge portion operates toblow air to the outside of the blade; and said pressure balance hole isdisposed on said back edge portion.
 8. The blade of claim 7, whereinsaid pressure balance holes are distributed in an array, uniformly orrandomly.
 9. The blade of claim 7, wherein said pressure balance holesare circular holes, non-circular holes, straight through holes orinclined through holes.
 10. The blade of claim 7, wherein said pressurebalance holes form a hole net whereby adjusting pressure on both side ofthe blade.
 11. The blade of claim 7, wherein a diameter of said pressurebalance hole ranges from 0.1 mm to 100 mm.
 12. The blade of claim 7,wherein said pressure balance hole is a circular hole or a non-circularhole.